Wedge or key for slotted dynamo-electric-machine elements



M. I. ILG.

WEDGE 0R KEY FOR SLOTTED DYNAMO ELECTRIC MACHINE ELEMENTS.

APPLICATION FILED MAY 27. l9l5- RENEWED SEPT-15,1920.

Patented Apr. 26, 1921.

UNITED STATES PATENT oFFIcE.

MAX JOSEPH ILG, or NUREMBERG, BAvAnrA, GERIEANY, AssrenoR T SIEMENS-Vscnucxnn'r WERKE e. M. B. H., or sIEMnNss'rAn'r, near-2. ans-LIN,GERMANY.

WEDGE OR KEY FOR SLOTTED DYN AIiTO-ELECTRIC-MACHIN E ELEMENTS.

Application filed May 27, 1915, Serial No. 30,844.

' To all whom it may concern:

and in order to be able to easily exchange parts of the winding whichhave become damaged, it is most convenient, to use socalled open slots,that is to say slots'of -'a cross-section which is not smaller at thetop of the slot than at the bottom, because the winding elements may bereadily inserted into and taken out of a slot of this kind.

Open slots on the other handhave the disadvantage that they do not givea sufiiciently large surface of the slotted iron body in order to have amagnetic path as large as possible for the entrance of the magneticlines of force into said body, thereby necessitating a larger size ofthe iron body and a surplus of ampere turns for generating the field.Also "other inconveniences are sometimes found in addition to this whenopen slots are used in dynamoelectric machine elements. r

Attempts have been made to avoid these disadvantages connected with openslots by closingthe slots by means of magnetizable wedges or keysafterhaving the winding inserted into the slots. Many forms of suchmagnetizable keys or wedges and many modes for keeping the samesafely'in position have been devised and employed in practice. Of allthese constructions, however, none has so far been able to fully meetthe teeth Z and Z there are provided. two

the practical requirements.

The object of my present inventionis to devise a key or wedge fortheslots of dynamo electric machine elements such as armatures, which morefully meets the practical requirements and which especially results in anumber of mechanical and magnetic properties that are not found in theordinary constructions; Y

My invention is an improvement of the ordinary slot-key generally of theshape of a 'flatlwedge, which consists in the first Specification ofLetters Patent.

Patented Apr. 26, 1921. Renewed sept'ember 15, 1920/ Serial No. 410,483;

place of magnetizable parts serving asa proper path for the lines offorce coming out of the teeth of the'slotted iron body or core, or inother wordsto increase the surface of said body for the'passageof linesof force; these parts may therefore be called the flanks of the wedge orkey. Secondly,

' this wedge or key consists of one or more parts which serve foruniting said flanks and therewith for retaining the shape of the wedgeas a whole, which latter parts may therefore be called bridges. ThisdistinciJlOIllbGtWGGIl the several parts of the slot' key 1s more fullyexplained by referring to F1gures 17 of the accompanying drawing.

In Flg. 1 a cross section 0f the 3 slot key is shown and in particularitis indicat-' ed in this figure how the lateral magnetizable ribs orflanks of the key affect the lines of force; V i i Fig. 2 shows a mentin Fig. l; Y

Figs. 3 andt' and 5 to. .7 show modificatlons of the forms of the keyadapted to be inserted into the slotsof dynamo-electrical machineelements according to the inven- 1310115 Fig. 8 showsthe manner ofplacing the key in'its seat, and- '1 c Fig. 9 shows a particularly:advantageous form of the key. i

In F igs. 1 and 2 a part of the slotted iron body or core liisindicatedas having a slot N between the two-'eteeth Z, and Z Fig. 2is a view of the surface of said slotted body K and Fig. 1 a section inthe plane of Fig. 2. v The slotsN is what is called an plan view of'thearrangeopen slot, for the width n of its -.crossi-s eetion (Fig. 1)at'the surfaceof K is not smaller than the width 'n at the bottom oftheslot'. The slot-is" closed by'a wedge or" key which is inserted intothe slot after the winding has been mounted therein. In

grooves 7", and 1, preferably of wedge-e shaped cross-sectionwhich'serve fori'receiv ing the wedge or key' V, thus forming a I seatfor firmly retaining the same in positlon. The wedge V properconsists ofthe flanks'e and a, and the bridges 7),, 6 ,6 h

keeping said flanks in 'positionffour such bridges'being shown in thedrawing The number of these bridges of course maybe chosen as desired,also only one bridge may be employed. In F ig. l I have shown how thelines of force I", f pass from the teeth Z Z through the flanks a a ofthe wedge or key V and how the surface of the teeth is increased therebyfor the passage of the magnetic lines of force.

The flanks of the wedge or key must be of magnetizable material in orderto serve their purpose, while the bridges are used only for mechanicalpurposes and therefore do not need to be of such material. These bridgesmay however be of magnetizable material and may be connected with theflanks in any manner. In case of a wedge or key which is made fromlaminated iron sheets, such as represented in Figs. 3 and 4, the. middleparts of the laminae, for instance that portion within the range of thelines a and 4:, shown in the drawing, ma be regarded as individualbridges or all tiese parts together may be considered as a singlebridge. With the wedge or key of the kind shown in Figs. 5 and 7,whereby the laminated flanks a and (1 are kept together by means ofconnection pieces of a shape according to' Fig. 6, the middle part I) ofthese connecting pieces will then have the function of said bridges.

According to my invention now at least the magnetizable flanks of thewedge or key shall be of laminated construction and at the same time theshape and material of the bridges shall be such that said bridges can bestretched by a proper tool, so that they will remain in stretchedcondition and that the flanks will firmly fit the grooves of the teeth.These bridges therefore must be of malleable material and must not beresilient, so that they will be readily deformable without againassuming their original shape, The malleability of the bridges accordingto my invention is utilized for fastening the wedge or key within thegrooves provided on the upper part of the teeth and more particularlythis is accomplished in the following manner The wedge or key is made ofa width which is slightly smaller than the contour of said grooves, z'.6., of its seat, so that the key may easily be inserted. Thereupon. thewidth of the key is increased by stretching the bridges, which'causes itto become firmly jammed into its seat.

Since the material of the bridges as above stated must be malleable, awedge or key which is made of softyiron according to Figs. 3 and 4 willimmediately satisfy this condition. In case of a wedge or key havingnon-magnetic bridges, such as for instance shown in Figs. 5, 6 and 7,brass, German silver or the like. is used for the bridges. Regarding theshape tobe chosen for the bridges according to my invention it is mostadvantageous to make the bridges somewhat arched, so that by exerting aproper pressure on them they will be stretched and will force the flanksto firmly fit into the grooves provided at the upper end of the teeth.It is also preferable, if bridges are used similar to those illustratedin Figs. 5, 6 and 7 to arch both their upper and lower faces in the sameoutward direction, because in this case the stretching of the bridgesfor fastening the same between the teeth can be accomplished in a verysimple manner by hammer blows.

Fig. 8 represents my invention in the just mentioned modificationapplied to a wedge or key of the kind shown in Figs. 5, 6 and 7. Thebridges b of the wedge or key V, as seen from the front, are outwardlyarched in the same direction on both their upper and lower faces. Asshown in this figure the wedge or key will still be lying loosely withinits seat after having been inserted in a direction,perpendicular to thedrawing. The grooves r r, are usually lined with insulating sheets 71,and i such as for instance paper. For fastening the wedge or key thearched bridges b are stretched by a pressure or a hammer blow which isexerted thereon in the direction indicated by the arrow P. This willcause the flanks a arrows Q, B, so that they will be pressed firmly intothe grooves r r Tam aware that it is known to employ laminated slot keysor wedges, and also to spread such keys or wedges into their seats.According to my invention the key for closing the slot is so constructedthat at least the flanks are made from laminated material and that thekey as a whole is spread into'the slot which results in the advantagethat the insulating' sheets between the key and its seat (i '5 Fig. 8)may be chosen extremely thin. This insulation must be present in orderto prevent eddy-currents from-being generated during operation in theordinarily'laminated teeth of the. slotted dynamo body or element, ifbetween the sev-.

accomplished. The insulation should be as thin as possible, in orderthat the magnetic lines of force in passing from the flanks of the wedgeor key into the teeth of the slotted body shall meet as littleresistance aspossible. If the key is driven into its seat from the sidethe insulation will be very heavily strained especially in case the keyis made from laminatedmaterial, because the edges of the several laminaewill act not unlike the teeth of a' file. The insulation would thereforehave to be comparatively thick, If a key having solid flanks" is spreadinto the seats the pressure of the flanks will as a rule be received by.the several laminae of the teeth, which always project from-the othersby reason of inevitable inaccuracies,

these places, the insulation againjmustbe comparatively thick. Ifhowever according to my invention a laminated key is spread into itsseatjthe flanks will beabletofit the unevenness of the surfa'cesfof the'seats, becausethe flanks are to a certain extent pliable. Thispliability is caused by the fact that the several laminae can bedisplaced relatively to each other and is duetoa certain extent to theflexibility of the rivet holding the several laminae togethenand to thefact that the several bridges may be stretched or deformed to adifferent extent. The pliability of the wedge or key effects a moreuniform distribution of the pressure upon the insulation and therebydoes away with the necessity of using a heavier insulation between thekey and its seat, such as in the case of solid flanks. The flexibilityof the laminated wedge or key has further the advantage that when thekey is spread into its seat it is very well secured against falling outof the slot, for a sort of toothed connection between the key and itsseat is made by the alternate recesses and projections which mesh witheach other and thus serve to safely hold the key in position.

The fact that the insulating sheets are very thin has a furtheradvantage in that the thin sheets do not even up the slight projectionsand recesses of the key and its seat, so that the aforementioned effectof the toothed connection will come more fully into action. Whenstretching the outwardly arched bridges 5, such as has been described onthe hand of Fig. 8, the flanks a and a make a small rotary motion in thegrooves 13 and 1' During this motion the insulating sheets i, and 2' maybe injured by sharp edges occurring at the flanks of the key. In orderto prevent this the profiles of the flanks and seats are rounded off andmore particularly at least at those points which will possibly slideupon one another during the operation of spreading the key into itsseat. An example of the rounded edges is shown in Fig. 9, the roundedoff points being shown at 0 and 0 The rivets for keeping the laminae ofthe flanks together are made from a tough material, such as tombac,bronze, German silver or the like. The cross-section of these rivets ispreferably of oblong shape, as shown in Figs. 3, 5 and 9. The heads ofthe rivets are most conveniently formed by simply bending down theprojecting ends of the rivet, shown in Fig. 8. The oblong crosssectionof the rivet in the first place prevents a rotation of the severallaminae relatively to each other and of the flanks relatively to thebridges in case a form is given to the key according to figs. 5, 6, 7and 8. Besides,

lines dff forc'e inthe flanks, as compared with rivets of roundcross-section having the. same mechanical strength. In additionto thisthe further advantage is secured that the bending strength of the rivetis increased in that direction in whichit is strained when the 'key isspread into its seat. v V Having thus described 'my -invention I claimnew 'and desire to secureby Letters Patent of the United'statesz 1 Awedge'or keyfon the slots ofdyna mo-electric machine elements,consisting of laminated magnetizable flanks, and bridges connecting saidflanks, said bridges being of malleable material, whereby said wedge orkey may be spread into its seat by deforming said bridges, substantiallyas described and for the purposes set forth.

2. A wedge or key for the slots of dynamo-electric machine elements,consisting of laminated magnetizable flanks, and bridges of a malleablematerial interposed between said flanks, said bridges being originallyarched in outward direction on the ends of said wedge or key, wherebysaid bridges may be deformedafter insertion of the key to keep the samefirmly in the slot.

3. A wedge or key for the slots of dynamo-electric machine elements,consisting of laminated magnetizable flanks, and bridges of malleablematerialinterposed betweenv rivets passing through the length of said 74. A wedge or key for the slots of dynainto its seat by deforming saidbridges, and

rivets of oblong cross-section passing through the length of saidflanks.

5. A slot key, comprising in combination, laminated magnetizable flanksand comparatively narrow deformable bridges connecting said flanks. V

6. Aslot key, comprising in combination, laminated magnetizable flanksand comparatively narrow deformable curved bridges connecting saidflanks.

7 A slot key, comprising in combination, laminated magnetizable flanksand deformable bridges connecting said flanks, said key being originallyarched.

8. A slot key, comprising in'combination, laminated magnetizable flanksand deformable bridges connecting said flanks, said bridges being shapedso as to spread said flanks apart upon being deformed;

9. A slot key, comprising in combination,

laminated magnetizable flanks, rivets passing through and holding saidflanks to-' gether, and comparatively narrow curved bridges connectingsaid flanks, said bridges being. shaped so as to spread said flanksapart upon being deformed, V

10. A slot key, comprising in combination, laminated magnetizableflanks, rivets of oblong cross-section passing through and holding saidflanks together, and comparatively narrow curved portions connectlngsaid formed.

In testimony whereof I have hereunto set my signature in the presence oftwo subscribing witnesses.

, MAX JOSEPH ILG.

' Witnesses: I Y

GEoRG WURZNER, J. MCNALLY.

